The cyclone collector collects dust and dirt (hereafter called as dust, collectively) from air by using the principle of cyclone. The cyclone collector has wide applications, and applied to the vacuum cleaner as a domestic application.
Currently, in order to improve dust collecting performance, the dual cyclone collector having a plurality of cyclone collectors connected to one another is used. That is, the dual cyclone collector is provided with an upstream cyclone for drawing air containing dust and the like (hereafter called as “dirty air”) and collecting comparatively large sized dust particles, and a downstream cyclone connected to the upstream cyclone for collecting relatively small sized dust particles. In general, the dual cyclone collector is provided with one upstream cyclone and one downstream cyclone. The downstream cyclone may have a plurality of small sized cyclones (hereafter called as “multi-cyclone collector”). An example of such a multi-cyclone collector is disclosed in Japanese utility model laid open publication No. S52-14775.
Referring to FIG. 1, a related art multi-cyclone collector will be described.
The related art multi-cyclone collector is provided with a cyclone 1 (hereafter called as “primary cyclone”) for drawing external dirty air, and collecting comparatively large sized dust particles, and a cyclone 3 (hereafter called as “secondary cyclone”) connected to the primary cyclone 1 for collecting comparatively small sized dust particles. The secondary cyclone 3 in the multi-cyclone is a group of small sized cyclones.
This will be described in detail.
The secondary cyclone 3 having a plurality of small sized cyclones is mounted on an outside circumference of the primary cyclone 1. The primary cyclone 1 has a first inlet 11 in an upper portion of a first body 12 of the primary cyclone 1 for drawing the dirty air in a tangential direction, and a first outlet 14 at a substantially central portion of the primary cyclone 1 for discharging primarily filtered air (hereafter called as “partially dirty air”) to the secondary cyclone 3. In general, the first outlet 14 is cylindrical, with an opened bottom 14b and no holes in an upper portion thereof. In some cases, a filter 16 is mounted on the opened bottom 14b. 
In the meantime, the secondary cyclone 3 has a plurality of small sized cyclones mounted on an outside circumference of the primary cyclone 1. Of course, each of the secondary cyclones 3 also has an inlet (not shown) and an outlet 34 (hereafter called as “a second inlet” and “a second outlet”). In general, between the primary cyclone 1 and the secondary cyclone 3, there is a buffering chamber 56 defined therein. Through the buffering chamber 56, air is introduced to the secondary cyclone 3 from the primary cyclone 1. Above the secondary cyclone 3, there is an outlet chamber 52 in communication with the second outlets 34 of the plurality of secondary cyclones 3, for discharging air dust collecting therefrom is completed (hereafter called as “clean air”) through an outlet tube 54 via the outlet chamber 52.
The operation of the related art multi-cyclone collector will be described.
Upon putting the multi-cyclone collector into operation, to drive suction force generating means, such as a suction fan (not shown) of the vacuum cleaner, the external dirty air is introduced into an inside of the primary cyclone 1 through the first inlet 11 of the primary cyclone 1. In this instance, the dirty air is drawn in a tangential direction, and swirls along an inside wall of the first body 12 of the primary cyclone 1, during which the dust is separated from the air by centrifugal force.
In this instance, comparatively heavy and large dust particles are collected on a bottom of the primary cyclone 1, and small dust particles not collected yet swirl the inside of the primary cyclone 1 until the small dust particles rise, and is discharged through the first outlet 14.
In the meantime, the partially dirty air discharged from the primary cyclone 1 is introduced into the secondary cyclone 3 through the second inlet (not shown). Eventually, the clean air having small sized dust particles separated therefrom at the secondary cyclone 3 once again is discharged to an outside of the collector through the second outlet 34, the outlet chamber 52, and the outlet tube 54.
However, the related art multi-cyclone collector has the following problems.
First, in the related art cyclone collector, air drawn through the inlet of the primary cyclone moves down to a lower portion of the inlet, and rises again, to escape from the cyclone. Though the dust is collected in this process, there is a pressure drop occurred in the process. That is, due to a great pressure loss, the related art cyclone collector is involved in drop of suction power.
Second, in the related art cyclone collector, the dust collected at the primary cyclone is liable to fly again, and move to the secondary cyclone. Moreover, since the air in the primary cyclone moves down to the lower portion of the inlet of the primary cyclone, the dust collected at the primary cyclone is highly vulnerable to re-fly.
Third, if a filter is mounted to the inlet of the primary cyclone of the related art multi-cyclone collector, the filter is liable to clog.